My money’s on dry egg, although milk is a possibility. A lot of commercial mixes in this vein are add-water-only.@ChrisC1234: This is true, but I’d think that pancakes are a bit more likely than some other products to be undercooked. I’m thinking of those big, thick ones that are still all batter-y in the middle…ish. Like eating paste.

@Eyebrows McGee: In addition to the fat present in whole wheat flours, since the entire wheat kernel is milled, the rancidity-causing enzymes in the bran are incorporated into the ground product. These are what actually cause the fat to go rancid. Interestingly enough, flour rancidity might not be an issue someday in the future. There’s a lot of research going on into the possibility of heat-treating the flour, which unfolds those enzymes and makes them unable to function.

You’re right in that rancidity isn’t a huge health risk, but it will wreak havoc on any baking soda that happens to be present, which means that your baked good/pancake won’t rise at all.